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Philosophy and Feasibility of Dual Readout Calorimetry

Philosophy and Feasibility of Dual Readout Calorimetry. The main simple idea is to measure a hadronic shower twice - as if two different calorimeters make an image of the same shower.

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Philosophy and Feasibility of Dual Readout Calorimetry

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  1. Philosophy and Feasibility of Dual Readout Calorimetry The main simple idea is to measure a hadronic shower twice - as if two different calorimeters make an image of the same shower. The first realization of this was the Dual Readout Module (DREAM) embedded with scintillating fibers and clear fibers (for Cerenkov light production) described by Wigmans, 7th Calorimetry Conf., Tucson, 1997. Scintillation light, S: all charged particles, mostly ±, some slow p Cerenkov light, C: charged particles above 1/n, mostly e± from 0 The main goal was to improve hadronic calorimetry without the constraint that the sensitive-medium-to-absorber ratio be compensating, e/h=1. J. Hauptman CALOR06 Chicago

  2. A few “applications” • DREAM-1 (Scintillation+Cerenkov, exact separation of light in separate fibers) • DREAM-2 (Scintillation+Cerenkov light mixed into the same fibers) • DREAM-3, PbWO4 (Scintillation+Cerenkov in one crystal: 4th concept, CMS-2) • TeV -ray astroparticle physics (Cerenkov+N2 fluorescence) • Muon identification (4th) (There must be a half-dozen more …) J. Hauptman CALOR06 Chicago

  3. This dual measurement doesn’t have to be just with light … • Dense spatial clusters: weight “EM” clusters [Abramowicz, et al., NIM 180 (1981) 429] • “two samplers”: nice early discussion of possibilities [Paul Mockett, Calorimeter Review, SLAC Report 267, 1983] • dE/dx & Cerenkov: in L-Argon calorimeter [Winn and Worstell, IEEE NS-36 (1989) 334] • Radial Scintillation & Cerenkov profiles [ DREAM “profile” paper, NIM A548 (2005) 336] J. Hauptman CALOR06 Chicago

  4. Mockett 1983 SLAC Summer Institute • “A technique is needed that is sensitive to the relative fraction of electromagnetic energy and hadronic energy deposited by the shower. This could be done hypothetically if the energy were sampled by two media: one which was sensitive to the beta equals one electrons and another which was sensitive to both the electrons and other charged particles. For example one sampler could be lucite which is sensitive only to the fast particles, while the other sampler could be scintillator. Then the fraction of pizeros produced could be determined from the relative pulse heights of the two samplers. Another technique might be to utilize the slow scintillation pulse and the fast Cerenkov pulse in total absorbing materials such as scintillating glass or Barium fluoride. By appropriate gating for wave form sampling …” J. Hauptman CALOR06 Chicago

  5. This dual measurement doesn’t have to be just with separate fibers, or “samplers” … • Mixed light in one set of fibers ( DREAM-2 ) • Mixed light in a single crystal ( 4th, CMS-2, DREAM-3 ) • Mixed light in the atmosphere ( TeV astrophysics ) • Mixed light in noble liquids … J. Hauptman CALOR06 Chicago

  6. But, you must separate the light …Cerenkov Scintillation • Physically, e.g., separate fibers clear fiber fiber with fluor • By direction: Cerenkov~450isotropic • By wavelength: d/2 ~ blue, UVgreen, etc. • By time: ~0~many ns • By polarization few % (avg) none J. Hauptman CALOR06 Chicago

  7. Physical separation DREAM J. Hauptman CALOR06 Chicago

  8. J. Hauptman CALOR06 Chicago

  9. DREAM: Cerenkov vs. scintillation signal 100 GeV - Raw data for 100 GeV - Cerenkov vs Scintillation signals, scale defined by response to 40 GeV e-. EM fraction fluctuations are obvious J. Hauptman CALOR06 Chicago

  10. Cerenkov signal is well correlated with EM fraction 200 GeV “jets” (e/h)S = S ≈ 1.4 (e/h)C = C ≈ 5.0 C = [fEM + (1-fEM)/C] E S = [fEM + (1-fEM)/S] E C/E = 1/C + fEM(1-1/C) J. Hauptman CALOR06 Chicago

  11. DREAM data 200 GeV π-: Energy response Scintillating fibers Scint + Cerenkov fEM  (C/Eshower - 1/hC ) (4% leakage fluctuations) Scint + Cerenkov fEM (C/Ebeam - 1/hC) (suppresses leakage) J. Hauptman CALOR06 Chicago Data NIM A537 (2005) 537.

  12. More important than good Gaussian response:DREAM module calibrated with 40 GeV e- into the centers of each tower responds linearly to π- and “jets” from 20 to 300 GeV. e- Hadronic linearity may be the most important achievement of dual-readout calorimetry, so far. J. Hauptman CALOR06 Chicago Data NIM A537 (2005) 537.

  13. Deliberately mixing the light S+S = pure scintillation C+C = pure Cerenkov S+C+C = mixed light 3 PMTs 3 PMTs J. Hauptman CALOR06 Chicago

  14. Separation by direction: mixed light DREAM-2 test, scintillation and Cerenkov light deliberately mixed in same fibers J. Hauptman CALOR06 Chicago

  15. Time separation: DREAM-2 module,mixed lightin fibers Most of the light is inside 10-15 ns. A deliberate design would improve this separation. These signals were digitized at the ends of long cables. J. Hauptman CALOR06 Chicago

  16. Light mixed in a single macroscopic medium J. Hauptman CALOR06 Chicago R.Wigmans Elba ‘06

  17. J. Hauptman CALOR06 Chicago R.Wigmans Elba ‘06

  18. J. Hauptman CALOR06 Chicago

  19. Slope dL/dt measures C/S J. Hauptman CALOR06 Chicago

  20. J. Hauptman CALOR06 Chicago

  21. “Lamborghini” model crystal(CMS-2 ?) S2 C2-C1 ~ Cerenkov (S1+S2)/2 ~ Scintillation PbWO4 crystal C2 • (S2-S1)/(S2+S1) • = ~light depth • atten. correction  improve E/E C1 Filter+APD Filter+APD S1 And, vs. S  monitors rad damage particle direction J. Hauptman CALOR06 Chicago

  22. TeV particle astrophysics: separate  from proton, He, and more … problem at the Greisen (GZK) limit ? • Index of air n=1 +.00029NTP • Cerenkov th=1/n N2 line emissions 300-400 nm and with lifetimes of several ns -ray proton J. Hauptman CALOR06 Chicago

  23. Hadronic showers in the atmosphere: separate by time and wavelength Scintillation light for N2 fluorescence … (green and slow) Pancake of Cerenkov light (~1m thick) … (blue and fast) J. Hauptman CALOR06 Chicago

  24. Fluxes and energy thresholds • N2 fluorescent yield: 0.02 pe/GeV • Use Cerenkov trigger to open N2 fluorescent gate for only 10-20 ns, so background is negligible • This trigger Lowers energy threshold from 1018 eV down to 1016 eV, or lower • Larger light gathering area … down to 1015 eV? Goals would be to (1) discriminate -rays from protons and (2) make better hadronic energy measurements J. Hauptman CALOR06 Chicago

  25. Muon dual-readout identification The Cerenkov signal from an aligned, non-radiating muon is zero Photons at Cerenkov angle Cerenkov (clear) fiber Numerical aperture of fiber: “capture cone” +/- All of the Cerenkov light of an approximately aligned muon falls outside of the numerical aperture of the fiber. J. Hauptman CALOR06 Chicago

  26. Therefore, for a single  * dE/dx energy loss yields S=dE/dx and C=0 * Radiative energy loss inside calorimeter volume yields: S ~ C J. Hauptman CALOR06 Chicago

  27. Muons (40 GeV) & Pions (20 GeV) (S+C)/2 (GeV)     S-C (GeV)  S-C (GeV) J. Hauptman CALOR06 Chicago

  28. Muons and Pions (80 GeV)  (S+C)/2 (GeV)    S-C (GeV) S-C (GeV) J. Hauptman CALOR06 Chicago

  29. Muons and Pions (200 GeV) (S+C)/2 (GeV)  p m S-C (GeV) S-C (GeV) J. Hauptman CALOR06 Chicago

  30. Muons and Pions (300 GeV) (S+C)/2 (GeV)  p m S-C (GeV) S-C (GeV) J. Hauptman CALOR06 Chicago

  31. Summary … • In a fiber-calorimeter realization, dual readout is easy … “first shot” • Likely to be “easy” in an “EM calorimeter” crystal • Not restricted to n=2 (“dual”): why not n=3 “triple” readout of scintillation, Cerenkov and neutron signals in hadronic showers. • Not restricted to calorimeters: any measured quantity whose summed parts fluctuate benefits by those parts being separately measured. • It is a time to be clever … there are likely another half dozen ideas not yet conceived. J. Hauptman CALOR06 Chicago

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